The vitamin A status of infants (0.5-1 y), children (2-6 y) and pregnant women (15-30 y) of several raciocultural groups (Nonhispanic white, Hispanic, Afro-americans, and possibly Hmong Asians) will be assessed by a new validated method, the modified relative dose response (MRDR) assay. This method involves measurement of the ratio of 3,4-didehydroretinol (DR) to retinol (R) in plasma 5 h after the oral administration of a small, nontoxic dose of DR. The DR/R ratio, which increases as the vitamin A status worsens, usefully assesses marginal vitamin A status. An appropriate dietary questionnaire, including vitamin supplement usage, will be administered to adult women and to parents for participating children. An analogous procedure for assessing vitamin E status, involving a naturally occurring vitamin E analog, such as alpha-tocotrienol or delta- tocopherol, will be developed in rats. If animal results are promising, this vitamin E response (VER) test will be applied to the same human subjects. Finally, ethyl beta-apo-8'-carotene (BAC) will be tested as an indicator of the efficiency of fat absorption in a small group of adults. Thus, the goals are: 1. To use the MRDR to detect marginal vitamin A status in the target human groups, 2. To develop a similar dose response test (VER) for marginal vitamin E status in rats, and then to apply it to these same target groups, 3. To correlate the results of MRDR and VER tests with data obtained from a dietary questionnaire, and 4. To investigate the utility of a new BAC absorption as an indicator of the efficiency of absorption of lipids and fat-soluble vitamins in humans.